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Global warming may double El Niño frequency

Study findings suggest more Australian heatwaves

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New study analyzes how global warming will affect El Niño events.

By Summit Voice

FRISCO — Strong El Niños — along with the extreme weather events that are driven by those warm Pacific ocean episodes — are likely to double as the globe heats up.

“During an extreme El Niño event countries in the western Pacific, such as Australia and Indonesia, experience devastating droughts and wild fires, while catastrophic floods occurred in the eastern equatorial region of Ecuador and northern Peru,” said  CSIRO Dr. Wenju Cai, lead author of a new study published in the journal Nature Climate Change.

“We currently experience an unusually strong El Niño event every 20 years. Our research shows this will double to one event every 10 years,” said Dr. Agus Santoso, a climate researcher with the ARC Centre of Excellence for Climate System Science. The international research team also included scientists with the National Oceanic and Atmospheric Administration. Continue reading

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Climate: Is the Southwest ‘stuck’ in a drought pattern?

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NOAA’s winter outlook offers little relief for Arizona, New Mexico

By Bob Berwyn

FRISCO — Drought conditions may persist across the southwestern U.S. this winter and may redevelop across the Southeast, according to the seasonal outlook from NOAA’s Climate Prediction Center.

“Even though we don’t have La Niña, the atmosphere across the Pacific seems to be stuck in a La Niña mode … It’s been quite surprising to us, how persistent the pattern is,” said Mike Halpert, acting director of the Climate Prediction Center.

Parts of the Southwest, especially New Mexico, have been experiencing one of the driest periods on record, and Halpert said there is “decent agreement” in the CPC’s models on the climate signal that has resulted in the persistent trend. Continue reading

Climate study shows that deforestation of the Amazon could dry out the western United States

Shifts in precipitation patterns would have big consequences for agriculture, forests and municipal water supplies

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Research suggests that deforestation will likely produce a weather cycle over the Amazon consisting of abnormally dry air in the sun-scorched northern Amazon around the equator weighted by wetter air in the cooler south (left). The Princeton-led researchers found that the Amazon pattern would be subject to meandering high-altitude winds known as Rossby waves that move east or west across the planet (center). The Rossby waves would move the dry end of the Amazon pattern directly over the western United States from December to February, while the pattern’s rainy portion would be over the Pacific Ocean south of Mexico (right). Image courtesy Princeton University.

By Summit Voice

FRISCO — Continued deforestation in the Amazon region could have significant impacts on the weather in North America, according to Princeton researchers, who used fine-grained climate models to simulate how precipitation patterns could shift in the future.

Their findings suggest that  total deforestation of the Amazon may significantly reduce rain and snowfall in the western United States — specifically, 20 percent less rain for the coastal Northwest and a 50 percent reduction in the Sierra Nevada snowpack, a crucial source of water for cities and farms in California.

“The big point is that Amazon deforestation will not only affect the Amazon — it will not be contained. It will hit the atmosphere and the atmosphere will carry those responses,” said lead author David Medvigy, an assistant professor of geosciences at Princeton. Continue reading

Climate: El Niño unusually active in 20th century

New study may help show how El Niño will respond to global warming

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Tracking El Niño …

By Summit Voice

FRISCO — Powerful El Niño events during recent decades are outside the norm of the last 600 years, climate researchers said this week, after finding that the cycles of warmer-than-average sea surface temps in the equatorial Pacific appear linked to global temperatures.

“Our new estimates of El Niño Southern Oscillation (ENSO) activity of the past 600 years appear to roughly track global mean temperature,” said Shayne McGregor, of the University of New South Wales. “But we still don’t know why.”

The team of climate scientists, including researcher with the University of Hawaii International Pacific Research Center and the NOAA Geophysical Fluid Dynamics Laboratory, said their findings (published in Climate of the Past) help resolve some of the uncertainties surrounding historic ENSO cycles, which can trigger flooding and droughts across different parts of the world. Continue reading

How will global warming affect El Niño?

Study shows how external influences shape Pacific weather patterns

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New research may help show how global warming will affect El Niño.

By Summit Voice

FRISCO — By studying coral samples from a remote Pacific atoll, Australian researchers say they’ve found evidence that external influences can change the intensity of the periodic El Niño cycle. By extension, they said, human-caused global warming could also alter the pattern, though the observational record is too short to determine whether that’s already happening.

The research was led by scientist with the ARC Centre of Excellence for Climate System Science and  published in Nature Geoscience.

“Our research has showed that, while the development of La Niña and El Niño events is chaotic and hard to predict, the strength of these events can change over long time spans due to changes in the global climate,” said one of the paper’s authors, Australian climate researcher Dr. Steven Phipps. Continue reading

Summit Voice: Week in review

Climate, cannabis and apex predators …

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Whither the weather?

By Summit Voice

FRISCO — One of the top news stories in Colorado last week was the dramatic change in the federal government’s position on legal use of marijuana in Colorado. After decades of intolerance, U.S. Attorney General Eric Holder indicated that the feds won’t seek to challenge Colorado’s new pot regime — at least for now. That leaves the state free to administer recreational sales of cannabis, as long as there is a robust state-based regulatory structure. Read the Summit Voice story, which includes the full text of the new guidance from the feds: Feds ease stance on marijuana.

In a couple of email interviews, Summit Voice explored the seasonal weather outlook. Making forecasts three months in advance is dicey at best, an in the absence of a clear El Niño or La Niña signal, meteorologists are struggling even more than usual to pin down upcoming patterns: Climate: With no Niño — what’s a forecaster to do?

For Mexican gray wolves living in the southwestern United States, the news was good. Rather than fighting conservation groups, the U.S. Fish and Wildlife Service backed down in the face of several lawsuits to give the predators a little more room to roam in the deserts of Arizona and New Mexico: Mexican gray wolves will get more room to roam.

A forest study in the eastern U.S. has implications for forest management here in the West, as well, showing that, when it comes to biodiversity, forest species need a mix of towering old growth and cleared areas, which are seen as important for birds just before they migrate: Study: Forest clearings crucial for some birds. Continue reading

Climate: With no Niño — what’s a forecaster to do?

Fall and winter outlook still murky

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Seasonal weather forecasters look out to sea surface temperatures in the equatorial Pacific to get an idea of what weather patterns may bring.

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Without a stron El Niño or La Niña in the outlook, forecasters are not confident of projecting pronounced temperature or precipitation anomalies.

By Bob Berwyn

FRISCO — With no strong El Niño or La Niña on the horizon, forecasters are struggling even more than usual to develop seasonal outlooks for the western U.S. The periodic El Niño-La Niña cycle is a large-scale shift in the Pacific involving a complex interplay of winds, ocean currents and sea surface temperatures.

In the U.S. the warm El Niño phase is associated with wetter than average conditions in the Desert Southwest and California, and can result in below average precipitation in the Pacific Northwest.

La Niña, on the other hand, has been linked with Southwestern drought conditions and heavy precipitation in the Pacific Northwest. That persistent moist flow off the northwestern Pacific can also favor parts of Colorado with good winter snows, but the ENSO climate signal is more marginal in Colorado than in other areas. Continue reading

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